For true melee characters, those using swords, axes, and daggers to hit enemies, I suggest having a perk that comes from using the same weapon(s) for a long time. The more you use it the better you get with it. Add speed, damage, crit hits, blocking etc. You could have the weapon bonus scale by, time, number of battles, length of battles, monsters killed, etc or a combination of those. Maybe add a place where a character could "practice" with a weapon to gain skill based bonuses. This might alleviate the need to upgrade weapons or craft them to higher levels.
that's a fantastic idea and I'm wondering how I would implement it from a coding point of view
first idea:
for each weapon type there is a corresponding perk tree and a corresponding skill
the skill increases as you use weapons of that type
second idea:
make "weapon mastery" independent of class and skills
3rd idea, is how it is handled in the game currently
whenever you use light weaponry (swords, daggers, small axe, small mace) you get more proficient at doing so (you gain increased damage)
same for heavy weaponry (battleaxe, warhammer, greatsword)
every class, as stated above, has some preference towards weapon types. usually youll have two to pick from.
this is somewhat lame, because practicing with a dagger makes you better at using swords, but you still get to specialize into a weapon type via both class selection and perks.
which of the three options would you prefer, which seems most immersive, which makes most sense from a gameplay pov? for me the second option with weapon mastery makes most sense, and it's easier to implement than the first option. it's a pretty elegant solution, too.
even cooler: introduce a penalty to the player from the start of the game (all weapon damage -50%). in order to circumvent the penalty you have to train with a weapon type, say get at least 100 killing blows with a warhammer. with every killing blow your damage with warhammers is raised, so that in the end you'll have +50% damage with warhammers, but -50% damage with all other weapon types.
in all of my changes I try to stay ingame 100%. I will not be introducing any extra menus, MCM, sliders, nothing of the sort, which makes my approach a little more difficult.